forked from rpms/glibc
137 lines
5.2 KiB
Diff
137 lines
5.2 KiB
Diff
commit a5cd39541396b91d90cc611858ee7b3355fcfe47
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Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
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Date: Tue Aug 13 21:08:49 2024 -0400
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ungetc: Fix backup buffer leak on program exit [BZ #27821]
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If a file descriptor is left unclosed and is cleaned up by _IO_cleanup
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on exit, its backup buffer remains unfreed, registering as a leak in
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valgrind. This is not strictly an issue since (1) the program should
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ideally be closing the stream once it's not in use and (2) the program
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is about to exit anyway, so keeping the backup buffer around a wee bit
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longer isn't a real problem. Free it anyway to keep valgrind happy
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when the streams in question are the standard ones, i.e. stdout, stdin
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or stderr.
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Also, the _IO_have_backup macro checks for _IO_save_base,
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which is a roundabout way to check for a backup buffer instead of
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directly looking for _IO_backup_base. The roundabout check breaks when
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the main get area has not been used and user pushes a char into the
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backup buffer with ungetc. Fix this to use the _IO_backup_base
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directly.
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Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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(cherry picked from commit 3e1d8d1d1dca24ae90df2ea826a8916896fc7e77)
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(cherry picked from commit b9f72bd5de931eac39219018c2fa319a449bb2cf)
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diff --git a/libio/genops.c b/libio/genops.c
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index a5dd6a06d9e259d8..b5fc53fd1ef6e911 100644
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--- a/libio/genops.c
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+++ b/libio/genops.c
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@@ -796,6 +796,12 @@ _IO_unbuffer_all (void)
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legacy = 1;
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#endif
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+ /* Free up the backup area if it was ever allocated. */
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+ if (_IO_have_backup (fp))
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+ _IO_free_backup_area (fp);
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+ if (fp->_mode > 0 && _IO_have_wbackup (fp))
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+ _IO_free_wbackup_area (fp);
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+
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if (! (fp->_flags & _IO_UNBUFFERED)
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/* Iff stream is un-orientated, it wasn't used. */
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&& (legacy || fp->_mode != 0))
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diff --git a/libio/libioP.h b/libio/libioP.h
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index dc9a2ce9c8d7744c..bab5f3770f0760c4 100644
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--- a/libio/libioP.h
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+++ b/libio/libioP.h
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@@ -529,8 +529,8 @@ extern void _IO_old_init (FILE *fp, int flags) __THROW;
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((__fp)->_wide_data->_IO_write_base \
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= (__fp)->_wide_data->_IO_write_ptr = __p, \
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(__fp)->_wide_data->_IO_write_end = (__ep))
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-#define _IO_have_backup(fp) ((fp)->_IO_save_base != NULL)
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-#define _IO_have_wbackup(fp) ((fp)->_wide_data->_IO_save_base != NULL)
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+#define _IO_have_backup(fp) ((fp)->_IO_backup_base != NULL)
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+#define _IO_have_wbackup(fp) ((fp)->_wide_data->_IO_backup_base != NULL)
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#define _IO_in_backup(fp) ((fp)->_flags & _IO_IN_BACKUP)
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#define _IO_have_markers(fp) ((fp)->_markers != NULL)
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#define _IO_blen(fp) ((fp)->_IO_buf_end - (fp)->_IO_buf_base)
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diff --git a/stdio-common/Makefile b/stdio-common/Makefile
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index 08bedd01be61a55d..f10bf28878e0aebc 100644
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--- a/stdio-common/Makefile
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+++ b/stdio-common/Makefile
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@@ -201,6 +201,7 @@ tests := \
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tst-swscanf \
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tst-tmpnam \
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tst-ungetc \
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+ tst-ungetc-leak \
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tst-unlockedio \
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tst-vfprintf-mbs-prec \
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tst-vfprintf-user-type \
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@@ -229,6 +230,7 @@ tests-special += \
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$(objpfx)tst-printfsz-islongdouble.out \
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$(objpfx)tst-setvbuf1-cmp.out \
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$(objpfx)tst-unbputc.out \
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+ $(objpfx)tst-ungetc-leak-mem.out \
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$(objpfx)tst-vfprintf-width-prec-mem.out \
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# tests-special
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@@ -243,6 +245,8 @@ generated += \
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tst-printf-fp-leak-mem.out \
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tst-printf-fp-leak.mtrace \
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tst-scanf-bz27650.mtrace \
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+ tst-ungetc-leak-mem.out \
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+ tst-ungetc-leak.mtrace \
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tst-vfprintf-width-prec-mem.out \
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tst-vfprintf-width-prec.mtrace \
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# generated
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@@ -288,6 +292,9 @@ tst-printf-fp-leak-ENV = \
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tst-scanf-bz27650-ENV = \
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MALLOC_TRACE=$(objpfx)tst-scanf-bz27650.mtrace \
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LD_PRELOAD=$(common-objpfx)malloc/libc_malloc_debug.so
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+tst-ungetc-leak-ENV = \
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+ MALLOC_TRACE=$(objpfx)tst-ungetc-leak.mtrace \
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+ LD_PRELOAD=$(common-objpfx)malloc/libc_malloc_debug.so
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$(objpfx)tst-unbputc.out: tst-unbputc.sh $(objpfx)tst-unbputc
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$(SHELL) $< $(common-objpfx) '$(test-program-prefix)'; \
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diff --git a/stdio-common/tst-ungetc-leak.c b/stdio-common/tst-ungetc-leak.c
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new file mode 100644
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index 0000000000000000..6c5152b43f80b217
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--- /dev/null
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+++ b/stdio-common/tst-ungetc-leak.c
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@@ -0,0 +1,32 @@
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+/* Test for memory leak with ungetc when stream is unused.
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+ Copyright The GNU Toolchain Authors.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <stdio.h>
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+#include <mcheck.h>
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+#include <support/check.h>
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+#include <support/support.h>
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+
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+static int
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+do_test (void)
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+{
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+ mtrace ();
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+ TEST_COMPARE (ungetc('y', stdin), 'y');
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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